Messages wont stay deleted

I have an iPhone 4s and after downloading ios 7, I noticed I was unable to delete full conversations anymore. Whenever I swipe a conversation and press delete, it crashes my message app and then deletes all my conversations. When i restart my phone all my messages come back including the one I originally tried to delete.

Ive tried every way of deleting the conversations except deleting the texts one by one because some of the conversations are years long. I need to clear this space up too because my messages are almost taking up 2GB of my phone.

THIS PROBLEM ONLY STARTED AFTER IOS 7.